Automatic train-control system



Nov. 2, 1926.

C. BUSHNELL AUTOMATIC TRAIN CONTROL SYSTEM Filed March 14, 1921 Patented Nov. 2, 1926.

UNITED STATES 1,605,523 PATENT OFFICE.

CHARLES S. BUSHNELL, OF ROCHESTER, NEW YORK. ASSIGNOR TO GENERAL RAIL- WAY SIGNAL COMPANY, OF GATES, NEW YORK, A CORPORATION OF NEW YORK.

AUTOMATIC TRAIN-CONTROL SYSTEM.

Application filed. March 14, 1921. Serial No. 452,368.

This invention relates to train control systems, and more particularly to that part of the system, which may be termed the impulse transmitting means, and which acts to transmit or communicate the desired controlling impulses or influences from the trackway to the locomotives or other vehicles to be controlled.

On account of weather conditions, problems of clearness, and the like, it is desirable to transmit the impulses from the trackway to moving vehicles through an intervening air gap without physical contact, and one simple system of this inductive type comprises an electromagnet on the track, which is energized when it is desired to transmit the stopping impulse, and which acts to induce current in a coil or winding on the car and thus control a relay or similar device, or to attract a movable armature, or to produce in some other way an action on the car that can be utilized to control suitable mechanism for regulating the movement of the car. Such a simple arrangement, however, has the objection that it violates the principle of failure on the side of safety, because if the source of current for energizing the electro-magnet fails, the wires break or contacts fail to close, the stopping impulse will not be transmitted.

The present invention provides a simple and effective way whereby failures preventing energization of a track electro-magnet will be automatically detected and passing trains controlled on the side of safety. Other more specific objects and advantages of the invention will be explained hereinafter as the description progresses.

In the accompanying drawing, Fig. 1 is a diagrammatic view of a portion of track equipped in accordance with the invention, the device and circuits being shown conventionally and in a way to facilitate explanation and make it easy to understand the invention, rather than for the purpose of showing the exact construction and arrangement of parts preferably employed in practice; Fig. 2 is a similar view showing a modified arrangement of the parts and circuits at one signal location; and Fig. 3 is a diagrammatic view showing one form of the car equipment, together with another view of the track device, and illustrating the cooperative relation between the car apparatus and the track electro-magnet, the

controlling circuits for said electro-magnet being those shown in Fig. 2.

The invention is illustrated in the accom panying drawing in the form which it takes in connection with automatic block signal systems, but this particular construction is not compulsory.

Referring to Fig. 1, the track rails 1 are divided by insulated joints 2 into blocks in the usual way, one block I, with the adjacent ends of two other blocks H and J being shown. Since the devices and circuits associated with each block are the same, as a matter of convenience they will be given like reference characters with distinctive exponents. Each of these blocks is provided with the usual normally closed track circuit comprising a track battery 3, and a track relay 4-. While my invention may be used with or without the usual fixed trackway signals, such signals are shown conventionally and designated S. These signals S may be controlled in any suitable way in accordance with recognized practice; and for the purposes of explaining the nature of the present invention, it will be assumed that these signals S are the ordinary three-position semaphore type controlled by a line or distant relay D. The control circuits for the relay D andthe signal S being well known, need not be discussed in detail. It is noted here that for convenience the various circuits illustrated have been shown according to the convention in which the letter B designates a connection to one terminal of a battery or other source of electric energy, and the letter C indicates a connection to the other terminal of said source, either direct or through a common wire for the system.

According to the present invention, the track impulse device T is an electro-magnet and as shown, comprisesa U-shaped iron core 5, with enlarged pole pieces 6 (see Fig. In the arrangement shown in Fig. 1, there is one coil or winding 7 on each leg of the core 5, and these coils are wound'and connected in series so that when energized they act together to create a field of flux above said core. The coils 7 are energized from the track battery 3. The circuit connections will be explained hereinafter in the description of the operation.

Associated with each signal S is a circuit controller designated E as a whole, which is moved in correspondence with the move ment of the semaphore blade and is opened and closed at difi'erent positions in the travel of said blade. This circuit controller is shown in accordance with established convention as comprising an arm 8 making contact with arcuate segments 9 and 10 in different positions of the blade, namely, from degrees to 90 degrees, and zero degrees to degrees, respectively.

The arrangement shown in Fig. 1 operates as follows. When the signal S is in the clear position, that is, when neither the block I nor the block J is occupied, the battery 3 is connected directly across the track rails of the block H, so as to perform the usual function of a track battery for energizing the track relay of said block H. This partial circuit or connection may be traced as follows :com1nencing at the lower t IClI rail 1 of block H, wire 11, battery 3, wire 12, contacts 89 of circuit controller E (closed from degrees to 55 degrees) wire 13, adjustable resistance 1%, and wire 15 to the other track rail. The coils 7 of the track element T are deenergized.

lVhen the signal S is operated to either its caution or its stop position, due to the pres ence of a train in the block J or the block 1, respectively, the partial circuit just traced is interrupted at the circuit controller E,

and another partial circuit for applying voltage across the track rails of the block H is formed as followsicom1nencing at the lower track rail 1, wire 11, battery 3, wire 12, contacts 810 of circuit controller E (closed trom zero degrees to 60 degrees) wire 16, coils 7, and wire 17 to the other track rail. Thus with the signal S in either the caution or stop position, the coils of the track electro-magnet T are energized, and this creates a magnetic field above said magnet which will cooperate with a suitably constructed car equipment to transmit a stopping impulse. I

It will be observed that this construction serves to automatically checl: and detect any failure preventing energization of the track magnet T. Since the same battery 3, used for energizing the track magnet T governing' train movement into a block, is also used for supplying current to the track circuit of the block next in the rear, depreciation or failure of this'battery will be automatically detected and a train will receive a stopping impulse at the entrance to the next block in the rear; If the circuit controller contacts 8 1O establishing the energizing circuit tor the track magnet- T at entrance to block I should break, or for any reason tail to complete said circuit, or it the wires break, or the coils 7 become open circuited.-in short if anything happens to prevent the passage of the current through said coils 7then there will be no current delivered to the tra'ck'circuit of the block H, thereby automatically showing such failure at once by causing the train to receive a stop impulse at the entrance to said block H. ,l t is noted here that with appropriate windings and with the suitable receiving equipment on the car, the ordinary potash batteries, pretera bly two or more cells in parallel, vhich are ordinarily used in automatic block signal systems for the track batteries will ellicieutly serve the purpose of energizing the coils 7 or the track magnet. Also, it should be noted that little, it any, sore energy is taken from the track battery by the track electro-1na iet energized in accordance with the present invention, than in the ordinary track circuit, since the coils of said electro-magnet are merely substituted for the usual limiting resistance at certain times, that is, when the signalis at stop or caution. Further, it should be observed that the coils H v p 1 ol the track electro-magnct are normally deenergized, and are energized and deenern ized automatically by the passage of a trz n, so that the electro-ma net is consuming current only at th time it may be needed to stop a l ol lowing train.

lVhile the arrangement and proportionine; of the parts should be modi lied or selected to suit the varying working conditions occurring in practice, in order to obtain the best and most ellicient results, I find an organization approximately as follows worlrs satisfactorily under ordinary conditions. The core 5 is made of laminations, with about 17 spacing between its legs, and is approximately 5 square inches in cross section. The coils 7 are made to have a resistance of about to 1 ohm, and with the appropriate number of turns to produce rougln 1y 250 ampere turns in each coil, when cnergized by .65 volts ordinarily employed tor track circuit worlc. It should he understood that these quantities are merely illustrative, and may be readily modified by one skilled in the art in practicing; the invention.

In the modified arrz'inp ement shown in Fig. 2, there are two coils 20 and 21 on each of the yolve 5, and these coils are wourul and connected so that, when energized in multiple, the coil 20 opposes the coil 21, thereby producing no etlectivc field above the track magnet. The coils Qt) are connected in. series at all times across the tract: rails of the block next in the rear through the track battery 3, this connection heinoas follows: Commencing at the lower traclr rail '1, wire 22, battery wires 24- and 25, coils 20, and wire 26 to the other tr: cl; rail. The circuit controller 27, operated by the signal S, is closed between about (a) degrees and 90 degrees and cuts in the other coils 21 in multiple with the coils 20, when said signal is in its clear position, this connection being! as follows :Comn'iencing at the lower track rail 1, wire 22, battery 3, wire 24:, circuit controller127, wire 28, coils 21, and wires 29 and 26 to the other track rail. Under clear traffic conditions, therefore, both sets of coils 21 are energized and there is no magnetic field above the track element to 1 Il fluence the car apparatus on a passing tram. lVith the signal S in the caution or stop position, the circuit controller 27 isopen, so that the coils 20 alone are energized, and this establishes a field above the track element T for stopping passing trains.

lVith the two sets of coils 20-21 in multiple the resistance is one-fourth of that eX- isting when only one set of said coils is in circuit with the track battery 3, and to compensate for this variation so as to maintain substantially the same voltage across the track rails for operating the track circuit, a compensating resistance 30 is provided. This resistance 30 is connected at one end by wire 81 to one of the track rails of block H at one side of an auxiliary insulated joint 32 therein, and at the other end by wire 33, adjustable resistance 34., and wire 35 to the same track rail on the other side of said joint 32. The resistance 30 is shunted by the contacts of a circuit controller 36 operated by signal S and closed between about zero and degrees. The adjustable resistance 34 provides for any fine adjustment of the inter-rail potential required for the track circuit.

The modified arrangement shown in Fig. 2 operates in substantially the same way as that shown in Fig. 1, and needs nofurther explanation.

The magnetic field provided by a track magnet T in the active stopping condition may be detected on a passing car in various ways, either by-direct magnetic attraction (a movable armature), or by inducing a current in a car-carried coil; and the car equipment illustrated in Fig. 3 is merely a typical construction. Referring to Fig. 3, a magnetic yoke or core Y is supported in any suitable way from the frame work of a car with its pole pieces clear of any iron parts which would tend to divert flux. This yoke is carried so that its pole pieces pass directly over the pole pieces of the track element T. The air-gap between the car-carried yoke Y and the track element should preferably be made as short as the equipment and roadway clearances will permit. On each leg of the yoke Y is a receiving coil 40, and these coils are wound and connected so that when an energized track electro-magnet causes a change in flux through the yoke Y, the electro-motive forces generated in said coils will add together. 'VVhile this induced E. M. F. may be employed to oppose a battery or other suitable source of current in a circuit on the car and thereby cause a current change in the circuit suitable for dropping the armature of a relay having the appropriate operating characteristics, I preferably employ a device of the vacuum bulb or thermionic type, commonly termed an audion, to respond directly to the. induced E. M. F. and in turn control a simple tractive type relay, advantage being taken of the properties of the audion to control a current through the relay sufficiently large to permit the use of a simple and reliable device. Since the audion and its mode of operation is well known in the art, detail description is. unnecessary. The audion comprises a filament F, a grid G and a plate P. The filament F is heated by battery A, the grid G is connected in circuit with the receiving coils 40 and a battery C. The plate circuit includes the batteries B and C in series and the control relay B. Any suitable type of train control means may be governed by the relay R; and for the purposes of illustration I have shown a device K, in the form of an electro-pneumatic valve which, upon being deenergized, may immediately vent.the train pipe and apply the brakes, or set into operation any other suitable form of train control mechanism. The 'device K is normally energized by a circuit including the batteries B and G and the normally closed contacts of relay R.

Normally the battery C maintains a positive potential on the grid G with respect to the negative end of the filament F, and this causes current to flow in the plate circuit to maintain the relay R energized. When a car equipped as described passes an energized track electro-magnet T, one cycle of alternating current is induced in the coils 40 as they move into and out of the field of said track magnet. One-half of this cycle, either the first or the last, depending on the polarity of the track element, the winding of the coils l0, etc., opposes the voltage of the battery C and reduces the grid potential. This in turn reduces the current in the plate circuit, on account of the well known characteristics of the audion, and allows the armature of the relay R to drop, thereby deenergizing the device K' and setting it into operation. If the track magnet T is not onergized, no E. M. F. is induced in the coils 40, and the car passes over said track magnet without receiving an impulse,

The particular construction and arrangement of parts and circuit shown and described is susceptible of various modifications and adaptations, without departing from the invention. For example, contacts operated by the track and line relays may be used instead of the circuit controllers oper ated by the signals; and in the n1odification shown in Fig. 2, the resistance 30 may be inserted directly in circuit with the coils 2021, instead of beingconnected across an additional insulated joint 32. I desire to have it understood, therefore, that these various modifications, and others which will be ill ' iSQ readily apparent to those skilled in the art, all come within the scope of my invention.

What I claim is 1. In a train control system for railroads divided into blocks, the combination with train control means on a car responsive to magnetic flux transmitted thereto from the traclrway, of a track magnet associated with each block, an energizing circuit therefor, and means for placing the track magnet ot the block next in the rear in the stopping condition when current does not liow in the energizing circuit of any given track mag net under dangerous trafiic conditions.

2. In an automatic train control system for railroads having tracks divided into blocks each provided with a track circuit, an electro-magnet along the track near the entrance to each block, an energizing circuit for said magnet, and means whereby the track circuit current to the block in the rear is cut off when current does not flow in the energizing circuit of a given magnet under certain tralfic conditions.

8. In a train control system for railroads divided into blocks each having a normally closed track circuit, an electro-magnet at the exit end of each block for controlling the movement of trains into the nextiblock in advance, a battery for supplying current to the track circuit of each block, and means for including said track battery in circuit with the corresponding electro-magnet without interrupting the flow of current in said track circuit when the next block in advance is occupied.

4. In a train control system for railroads having tracks divided into blocks, an electromagnet near the exit end of each block, a track battery and a circuit including limiting resistance for normally supplying current to the track rails of each block, and trafiic controlled means for interrupting said circuit and establishing another circuit for supplying current to the track rails of said block, said another circuit including the coils of the corresponding electro-magnet.

5. In a train control system for railroads having tracks divided. into blocks each provided with a normally closed track circuit, a track battery and a limiting resistance for each track circuit. an electro-magnet near the entrance to each block adapted when energized. to communicate a stopping influence to a passing train, the winding of the electro-magnet having a resistance substantially equal to the limiting resistance. and automatic means governed by the track circuit of a block for substituting the winding of the electro-magnet at the entrance to that block "for the limiting resistance of the track circuit next in the rear without interrupting said track circuit.

6. An automatic train control system for railroads having tracks divided into blocks ncoasas each having a normally closed track circuit, comprising, an electro-magnet near the entrance to each block and controlling train movement in that block, a battery for supplying current to the track circuit of each block, and trafiic controlled means for utilizing said battery of any given one of said blocks to supply current to the electro-magnet controlling train movement into the block in advance of that given, providing either the first or second block in advance of the given block is occupied.

7. A train control system for-block signaling systems comprising an electro-magnet associated with each block and automatically included in the track circuit of the next block in the rear under dangerous trailic conditions, said magnet acting as a limiting resistance for the track circuit.

8. An automatic train control system for automatic block signal systems operated by track circuits comprising normally deenergized, electro-magnets adapted to establish fields of flux for stopping trains, and control means governed automatically in accordance with traific conditions for at times including said electro-magnets in the track circuits, whereby the energization of said electromagnets is automatically detected.

9. In a train control system For railroads having tracks divided into blocks each provided with a track circuit, a normally deenergized track impulse device associated with each block and adapted when energized to comn'iunicate a stopping influence to a passing train, and automatic means governed by the track circuit of a block for automatically connecting the impulse device of that block into the track circuit of the block next in the rear without interrupting that track circuit. whereby said impulse device is automatically energized when needed to protect a train and also has its energized condition automatically checked.

10. In a train control system, the combina tion with a track electro-magnet for at times establishing a field of flux for controlling trains, car-carried means responding to said field of flux and comprising a normally energized eleetro-responsive device, and a vacuum tube amplifier, said electro-responsive device being deenergized as the car-carried means is influenced by the trackway field of flux.

11. In a train control system, the combination with a track element establishing a magnetic field when in the active stopping condition, 0t car-carried means for detcrtin; said field comprising, a core, a normally energized winding thereon, an energizing circuit for said winding, a normally energized electro-responsive device, and a vacuum tube amplifier having its grid connected to said energizing circuit and its plate to said electi'o-responsive device, the passage 01: said car-carried means through the magnetic field of the track element acting to vary the grid potential and cause deenergization of said electro-responsive device.

12. In an automatic train control system for railroads having tracks divided into blocks by insulating joints, a track circuit for each block including the track rails and a track relay in series, a source of current for energizing said track circuit continu ously and Without interruption, a Wayside signal at the entrance of each block controlled to give indications corresponding to traffic conditions ahead, an inductive track- Way device near the entrance to each block for inductively transmitting control influences to a moving train under adverse trafiic conditions ahead and including a coil, and automatic means for preventing the signal of each block giving a favorable indication of trafiic conditions after the passage of a train beyond the limits of the zone normally controlling said signal unless the coil of the trackivay device in the corresponding block is intact and current may flow therein.

13. An automatic train control and Wayside signalling system for railroads having tracks divided by insulating joints into blocks, a Wayside signal for each block for indicating conditions of traflic ahead, a circuit Which controls the indication of such Wayside signal and in which current must flow to permit said signal to give a favorable indication of traffic conditions, a trackway device for inductively transmitting control influences to passing trains under predetermined traflic conditions ahead including a coil, said coil being normally entirely deenergized, and automatic means rendered effective by the passage of a train for temporarily including said coil in said circuit, whereby accidental breakage of the continuity of said circuit manifests itself by a sig nal indication adverse to that of existing traffic conditions ahead.

14:, An automatic train control and Wayside signalling system for railroads having tracks divided by insulating joints into blocks, a Wayside signal for each block for indicating tratiic conditions ahead, control circuits for said signals, trackWay devices for inductively transmitting control influences to passing trains under predetermined traflic conditions ahead including a coil, said coil being normally entirely de-energized, automatic means for including each coil in turn in a signal control circuit during the passage of a train, whereby accidental breakage of the continuity of said coil manifests itself 'by a signal indication more unfavorable than required by actual traflic conditions.

In testimony whereof I affix my signature.

CHARLES S. BUSHNELL. 

